* {
  margin: 0;
  padding: 0;
  list-style: none;
}
.app {
  width: 100%;
  height: 100vh;
  display: flex;
  flex-direction: column;
}

.footer,
.header {
  height: 50px;
  line-height: 50px;
  background-color: lightsalmon;
}
.main {
  flex: 1;
  overflow-y: auto;
}
.footer button {
  outline: none;
  border: none;
  background: none;
}
.list_item {
  padding: 20px;
  border-bottom: 1px solid #ccc;
}
